While the purpose of dental anesthesiology is to maintain the comfort of the patient and to allow proper treatment of the patient, it is traditionally associated with suffering and discomfort. In fact, dental professionals have observed that anesthetic injection commonly results in negative reactions and anxiety in patients, especially children.
The traditional device for injecting anesthetic solutions has been the manual syringe. The manual syringe has been a relatively effective device for administering anesthesia. However, since the syringe is operated manually, the rate and force of the injection vary.
The method of this invention overcomes the limitations of the traditional methods by employing a precisely controllable programmable medical liquid injector.
In a first embodiment of the method, the tissue is topically anesthetized in the region of puncture. Then, after a few seconds, a few drops of anesthetic are injected in the gingival papilla (for inferior molars) or, in the limit between the attached and the free gingiva (for other teeth), through the needle of preferably a programmable injector. The needle is then removed and then reinserted slowly, after the anesthetic has taken effect, into the alveolar crest (for the inferior molars) or, into the subperiosteal, next to the radicular apex (for the other teeth), while maintaining the anesthetic flow rate at approximately 0.3 ml per minute.
In a second embodiment of the method, the needle of the programmable injector penetrates the periosteum and the anesthetic is injected under the periosteum. This sub-periosteal anesthetic technique generally requires a low quantity of anesthetic, which is desirable to minimize toxicity and other possible negative effects of the anesthetic, and to decrease the time require for post-operative recovery.
Prior known subperiosteal anesthesia techniques can result in distension of the periosteum. Specifically, with prior techniques, subperiosteal injections can cause a detachment of the periosteum from the subjacent osseous layer to which the periosteum is firmly attached. Other possible negative effects include ischemia and necrosis of the periosteum tissue. These effects can cause instant, as well as post-operative pain.
For the above reasons, doctors have heretofore avoided subperiosteal anesthesia, preferring supraperiosteal anesthesia. Doctors have considered subperiosteal anesthetic injection a "complementary" technique only to be used if other "conventional" techniques are unavailable.
Studies on the administration of anesthetic determined a close relationship between dosage requirements and effectiveness, and the velocities of administration of the anesthetic drug. It has been determined that excessively rapid or large injections can tear away tissues due to excessive pressure, causing inflamed areas and necrosis in the tissue, as well as discomfort to the patient.
The recommendation is that one should make soft and continuous movements, not just in the needle introduction but also during the administration of the anesthetic drug. However, due to the various levels of skill and dexterity of dental professionals using traditional equipment, such as the manual carpule, it is often not possible to achieve soft and continuous movements on a consistent basis.
A computerized system of anesthetic injection is marketed under the name Control-Inject. This device allows precise speed control of anesthetic injection, and due to its computerized speed control system, has given the possibility, through studies,to find the ideal speed of anesthetic injection for different situations usually found at the dental office. So far, these studies have brought new results of great importance for the comprehension of the anesthetic's physiology in the human body.
One of these new results is based on the relationship between the speed of injection and the osseous tissue's capability of absorbing the anesthetic liquid when applied in the bone or in the periosteum. Before the invention of the Control-Inject anesthetic injector, it was thought that all the applications in osseous sites unavoidably would present strong pain, caused by the tearing away of the periosteum during the deposition of the anesthetic solution. With the resources from this injector, it was determined that, at the constant velocity of 0.3 ml per minute, all the volume deposition in the osseous site is absorbed by the bone. Thus, the periosteum does not tear away, enabling a painless injection either during the application or post-operative.
Besides that, the fact that there is no anesthetic reflux, and all the deposited volume is completely utilized, allows a great reduction in the dose required in the dental treatment. Small doses mean small risks. Injection at the controlled slow speed makes the traditional painful applications like the ones applied at the palate, the subperiosteal and intraligamentary injections, much more comfortable for the patient.
Recognition of the uniformity of good performance in osseous or periosseous anesthetic application techniques resulting from injection of anesthetic at a maximum rate of 0.3 ml per minute made possible the development of a practical, compact and simplified anesthetic injector which is the subject of patent application Ser. No. 09/113,843 filed Jul. 10, 1998.